There currently exists no dependable stethoscope for use in high noise environments. All available models suffer sound degradation at one or more points when used in the presence of high ambient noise. Unfortunately, patients in such environments are often critically ill, and the stethoscope remains a key tool in their immediate evaluation and treatment. Any improvement in the physician's ability to accurately auscultate heart and lung tones in these patients will translate into immediate benefits in patient care. We have designed an electronic stethoscope which combines noise subtraction at the chest piece with active noise cancellation at the ear pieces. The sound of our model will be similar to that of traditional units, but will be cleaner and slightly louder. The physical shape and feel will closely approximate current standard models. Our product will be useful in helicopters, fixed wing transports, ambulances, and loud emergency departments. Should our design be totally successful, we anticipate interest among physicians who must examine children and other patients unable to maintain silence during auscultation.